After technical and supply-chain problems postponed delivery of Boeing’s latest and greatest airplane for more than three years, the 787 Dreamliner program has had a mostly positive 2012.

Plane problems

Shimming: In February, Boeing admitted “incorrect shimming was performed on support structure on the aft fuselage of 787s.” That faulty spacer work was performed in one of the North Charleston factories.Engine shaft: In July, the second Boeing 787 built in South Carolina experienced a fiery engine failure that prompted international headlines, then a National Transportation Safety Board investigation and a Federal Aviation Administration airworthiness directive.Cooling unit/electrical: In September, Indian media reported problems with the cooling and electrical systems on Air India’s first plane.Fuel leak: In November, Boeing recommended inspections of its fuel-line connections after it received reports of fuel leaks. On Wednesday, the FAA issued an airworthiness directive requiring inspections of the couplings, especially the lockwires that help hold them together.Unknown: On Tuesday, a new United Airlines 787 had to make an emergency landing in New Orleans after a mechanical issue arose on its way from Houston to Newark, N.J. The exact cause has not yet been identified, but investigators are looking at a failed generator.READ MOREFor more coverage, go to

But while taking several steps forward this year, like delivering 35 planes to eight airlines, the jet program also has suffered the occasional stumble, including a couple this week.

On Wednesday, the Federal Aviation Administration issued an airworthiness directive requiring inspections of the 787’s fuel line connections.

It is the second 787-related “AD” in four months. The second S.C.-built 787 experienced a fiery engine failure during pre-flight taxi tests in late July that led the FAA in September to require repetitive checks of the GE-made engines.

The new directive came a day after a weeks-old United Airlines 787 had to make an emergency landing in New Orleans after a mechanical issue arose on its way from Houston to Newark, N.J.

The jet landed safely, and the passengers continued their journey on another plane. While the exact cause has not been determined, investigators found that one of the jet’s six electrical generators failed, the Seattle Times reported Wednesday.

Scott Hamilton, a longtime Boeing watcher, called the issues “new-airplane bugs.”

“If more of these show up, there could be some passenger avoidance, but I’d say it’s too soon to worry about that,” Hamilton, of the Issaquah, Wash.-based aviation consulting firm Leeham Co., wrote in an email.

This week’s directive, or AD, applies only to U.S.-registered planes, the three delivered so far to United, but it follows a Nov. 25 recommendation from Boeing to all its 787 customer airlines to perform the inspections and any necessary fixes.

“We are issuing this AD to detect and correct improperly assembled couplings, which could result in fuel leaks and consequent fuel exhaustion, engine power loss or shutdown, or leaks on hot engine parts that could lead to a fire,” the FAA directive stated.

Hans Weber, an airplane engine expert in California, said the latest airworthiness directive is “sort of embarrassing for Boeing.”

“But it’s not a big deal,” said Weber, president of TECOP International Inc., calling the fuel line problem “readily checkable and it’s readily repairable.”

The directive was prompted by reports of fuel leaks on two in-service 787s. Subsequent inspections showed several improperly assembled couplings on in-service and production airplanes, according to the FAA.

The couplings, as well as several other system connections, are housed in pylons that connect the engines to the wings, said Lori Gunter, a Boeing spokeswoman.

There are two fuel lines, one rigid and one flexible, that feed the fuel from the wing into the engine, Gunter said, and both couplings have had problems.

They have included couplings with missing or improperly installed lockwire, which holds the tubes tightly together; other parts within the coupling installed in the wrong locations; and incorrect or extra parts installed in the couplings.

The FAA said the AD is necessary because the “unsafe condition ... is likely to exist or develop in other products of the same type design.”

Gunter said the defects have been traced to workmanship issues, not design flaws.

“What we’ll do is look at the work direction and make it really clear,” Gunter said, referring to the building documentation and hinting at the possibility of more training.

Weber speculated that the fuel line problem could be another side effect of the 787’s ambitious global supply-chain strategy, where major components like the wings and engines come in fully assembled and Boeing must piece them together on its final assembly lines in Washington state and in North Charleston.

“I would start looking at who supplies what, who assembles it, and look at the instructions that these people were given,” he said.

Gunter declined to reveal whether the poor workmanship occurred in Washington or in South Carolina, calling it “immaterial.”

“We’re not answering that question because it really doesn’t matter,” she said. “It’s one production system.”

She also wouldn’t say which airlines experienced the fuel leaks and said there would be no further specifics on subsequent findings.

The directive requires airlines ensure the lockwire is installed correctly within seven days and that they inspect the assembly of the couplings within 21 days.

Gunter said more than half of the 38 Dreamliners in service have been inspected and that Boeing will inspect all the 787s still at its plants before delivering them.

The airworthiness directive will cost an estimated $900 per airplane, a tiny sum compared with the $206.8 million current list price of the jet model.

A Boeing South Carolina spokeswoman did not respond to a call Wednesday about this week’s issues.

The North Charleston complex delivered the first locally assembled 787 on Oct. 5 and was scheduled to deliver another plane that month. But all that has happened since has been test flights, including Tuesday and Wednesday.

Reach Brendan Kearney at 937-5906.